So, the amount of sugar in my grapes is rising nicely. Yesterday I checked one of them and it had about 82 Oe. The question is how to decide when to harvest? I discussed it with a friend of mine the other day and he suggested I checked the colour of the pips to judge if there is physiological ripeness, in which case the pips should have turned brown instead of green. In reality, as usual, it wasn't quit as easy as that when I looked at the pips, since they indeed were brownish, but also a bit green in some parts. I attach a picture of them. Could anyone help my how I should decide when to harvest?

Anders,For me, this is the hardest and most impostant call in winemaking.Most people I know do it on taste and visual appearance coupled with brix.A few take grapes from both sides of the rows and in different parts of the vineyard, put them in a blender and send the juice to the lab for analysis.Neither are perfect, in and of themselves, as the history of the vineyard is also a factor.In any event, I wish you luck.Best, Jim

Hi Anders, I can't help you much here with the ripeness question, but the 82 Oe made me do an exercise in conversion. I never use that scale or S.G. either, but I figured it out. 82 Oe is the same as and S.G. reading of 1.082, which translates to about 19.7 Brix (% sugar), which is the scale I always use. The Riesling I get from the Niagara Peninsula is usually around 21 Brix or 87 Oe and it has a good acid balance.

Hej Anders,nice to see that your vines are doing so well. Sixteen years ago a friend of mine and I harvested Riesling grapes in Fjärås (southern Sweden) in the beginning of December. The intention was indeed to make ice wine, but sadly the fermentation never got going, as we wanted to rely on indigenous yeasts. The must - and the experience! - was great, though.

The "pip" identification method has been going around the wine world in the past couple of years. I took a seminar two years ago by one fellow behind the method.

First, it requires more than looking at pips from one or two grapes. It requires, as Jim said above, taking samples from the vineyard. The trick is: the samples have to be random, and there's an ostensible method for that, too.

Second, we were given a bunch of samples at the seminar to test for maturity and in not one case was a pip fully brown which, I understand may never be reached in a cool growing climate, in which i reside, and where the seminar was held--actually, it was held at Cornell University's Agricultural research Station.

The absolute best method of determining maturity seems to be experience: visual and taste. But of course, that doesn't help someone new to the situation.

In my view, and what that may be worth you'll probably never know, the method best is to select a few bunches as randomely as you can, do the blending as Jim mentioned, read the numbers, and then taste. Try to remember that taste--you'll be building the experience with it.

This is all said in the assumption that this is your earliest experience with the grape.

The "pip" identification method has been going around the wine world in the past couple of years. I took a seminar two years ago by one fellow behind the method.

First, it requires more than looking at pips from one or two grapes. It requires, as Jim said above, taking samples from the vineyard. The trick is: the samples have to be random, and there's an ostensible method for that, too.

...

This is all said in the assumption that this is your earliest experience with the grape.

Thank you all for the input. As assumed, I am new to this situation, since this is my first harvest to come, so I need to build my experience to be able to judge the ripeness form the taste of the grapes. They do taste very sweet and not too acidic, I guess (or hope) the acidity is masked by all the sugar. And yes, Howie, there is in fact a Brix scale in my refractometer too, and your conversion seems to be right.

Anyway, Thomas, even though one really would need to sample and examine many pips, would you say that the two in my picture would be categorized as ripe? Or are they supposed to be even browner?/A

The "pip" identification method has been going around the wine world in the past couple of years. I took a seminar two years ago by one fellow behind the method.

First, it requires more than looking at pips from one or two grapes. It requires, as Jim said above, taking samples from the vineyard. The trick is: the samples have to be random, and there's an ostensible method for that, too.

...

This is all said in the assumption that this is your earliest experience with the grape.

Thank you all for the input. As assumed, I am new to this situation, since this is my first harvest to come, so I need to build my experience to be able to judge the ripeness form the taste of the grapes. They do taste very sweet and not too acidic, I guess (or hope) the acidity is masked by all the sugar. And yes, Howie, there is in fact a Brix scale in my refractometer too, and your conversion seems to be right.

Anyway, Thomas, even though one really would need to sample and examine many pips, would you say that the two in my picture would be categorized as ripe? Or are they supposed to be even browner?/A

Anders,

I wish I could answer that question. The pips simply don't tell the whole story, especially in a cool growing region.

Riesling, for instance, can reach its full flavor characteristics without having to reach the generally accepted physiological ripeness of some other varieties, and it can do it as low as 17 Brix--not that you want it to do it that way every year! But when it does, the pips are almost all green.

Did you read the latest article by Tom Stevenson about Riesling and maturity (petrol)? In it, he mentions the pip method--with disdain.

I don't harbor disdain for the method, but I also don't think it is fool-proof. As Riesling shows, physiological ripeness in the same grape variety may vary from location to location. Plus, there seems to be a range within which each variety has some play.

I'd say that if you have Riesling, and you have between 17 and 20 Brix, and you have total acidity between .8 and 1%, and you have a nice fruity flavor profile, you may have physiological ripeness (maturity); the numbers change per variety, of course.

Probably only in a warm climate do the pips turn completely brown every year, and probably only in a warm climate can you make a reasonable determination by that fact--but only probably.

I am probably old-fashioned or out-of-date but I rely on pH and sugar. For whites, a pH of 3.1 - 3.3, for reds a pH of 3.3 - 3.6, sugar usually whatever I can get between those numbers, usually 19 - 23 percent.

Alan Wolfe wrote:I am probably old-fashioned or out-of-date but I rely on pH and sugar. For whites, a pH of 3.1 - 3.3, for reds a pH of 3.3 - 3.6, sugar usually whatever I can get between those numbers, usually 19 - 23 percent.

To be sure--and if you have 17 to 20 Brix with total acidity between .8 and 1 %, pH between 3.0-3.2 is likely.

I learned of one unusual technique of evaluating grape maturity (in terms of both evaluating readiness for harvest and formulating specific grape batch treatment plans, post harvest) from a winemaker during an informal vineyard and winery walk. Fred Scherrer said he chews on the pips. I suspect this is not an isolated idea among winemakers.

Fred indicated that he accumulated some knowledge over time by doing this repeatedly, both pre- and post-harvest, with the grape sources he was handling. He said that he was able to better judge another aspect of the grape's build this way. He worked at the Dehlinger Winery and is owner/winemaker of his own Scherrer Vineyards operation.

Maybe this can help you, perhaps if not so much this year, but increasingly over time.

Good luck and happy pip munching !

"No one can possibly know what is about to happen: it is happening, each time, for the first time, for the only time."

I learned of one unusual technique of evaluating grape maturity (in terms of both evaluating readiness for harvest and formulating specific grape batch treatment plans, post harvest) from a winemaker during an informal vineyard and winery walk. Fred Scherrer said he chews on the pips. I suspect this is not an isolated idea among winemakers.

Fred indicated that he accumulated some knowledge over time by doing this repeatedly, both pre- and post-harvest, with the grape sources he was handling. He said that he was able to better judge another aspect of the grape's build this way. He worked at the Dehlinger Winery and is owner/winemaker of his own Scherrer Vineyards operation.

Maybe this can help you, perhaps if not so much this year, but increasingly over time.

Good luck and happy pip munching !

Jeff,What an interesting technique. I assume he's trying to determine phenolic ripeness and then assessing it vis-a-vis the taste of the pulp, brix, pH, etc. I'm not sure I'm that discerning but I can see where its possible and what better indicator of the phenolics then the pips and stems.Best, Jim

Physiological ripeness has become a clichéd buzz phrase. In practice, it refers to an inclusion of phenolic ripeness (as determined by skin tannins, and seed and stem colour and tannins) in the ripeness model and it has been used more for red/black grapes than for green/white (due to phenolic ripeness being of increased importance in red wines).

For Riesling in cool climates, 82 Oe is certainly reasonable (FWIW, it's firmly in the traditional Spätlese range). As Thomas has said, (1) you wouldn't really expect brown seeds from Riesling grown in such a climate at levels traditionally deemed "ripe" and (2) Riesling is capable of obtaining suitable aromatics at the sugar and acid levels considered suitable for the typical Germanic Riesling style (well before the seeds are turning the colour of brown associated with Cabernet Sauvignon or Zinfandel grown in California). A far better judge of ripeness in such grapes is the sugar (Brix/Oeschle/Baumé), acid (TA and pH) and flavour balance. The info you've given thus far suggests a suitable ripeness level, though if you want to be sure I'd suggest testing your TA and pH too (and, IMO, TA would be the more important of the two in your situation). HTH.

Ben Rotter wrote: . . . though if you want to be sure I'd suggest testing your TA and pH too (and, IMO, TA would be the more important of the two in your situation).

Why?Best, Jim

Jim,

I assume because the sugar appears high enough--based on Anders' comment about the taste--which would demand that the acidity be in reasonable balance. pH is closely related to TA as in, one goes down, the other goes up, mostly.

Ben may have had another reason, though.

PS: The "mostly" refers to those strange vintages when TA and pH go in the same direction--scary when that happens...

Last edited by Thomas on Sat Oct 04, 2008 6:14 pm, edited 1 time in total.

Hanna Instruments (or the likes) hasn’t come out with a “hand-held” photometer yet to determine “phenolic ripeness” or “physiological maturity”?One serious question;Phenolic compounds are found in the skins, pips (seeds), and stems, very little is found in the pulp. Do all three components actually reach “phenolic ripeness” at the same time?

Phenolic compounds are major wine constituents, not only are they responsible for color and astringency but they also contribute to some of the wine’s other organoleptic properties. The phenolic composition of the ”finished” wine is no doubt related to the level of phenolic compounds of the “raw material”. But more so, by the winemaking techniques or processes used to produce the wine (namely maceration (skin contact time post and pre fermentation), pressing (light or heavy, pre and post fermentation pressing), including or discarding stems, and might as well add the wine’s aging process).

You can't really tell pip ripeness from looking unless you suck off the pulp and then roll them in your hand. The easiest and fastest test is that a ripe pip tastes like popcorn when you bite into it. If you are picking a delicate white (I am guessing riesling?) that might actually be a little too developed. Since with whites you will not be hard pressing the pips/seeds, the issue is less critical than it is with robust reds which will be fermented as must and pressed off the skins and seeds after the softening action of fermentation.

Sorry, Mary, I've had one or two threads about my vine earlier, so I didn't think of specifying the variety. What I have is a single Riesling vine that has set fruit for the first time this year and it is growing against a south facing brick wall in Stockholm, Sweden, so actually far north of where it should really ripen. the special climate against that wall, however seems to be warm enough for it to ripen, at least judged from the sugar lever in the must, even though we have not had any particularly warm summer or autumn this year. Here is the latest picture I have of my tiny grapes, taken on thursday last week. They are about half an inch in diameter.

thanks everyone for all the insight about how to decide when to pick. Although I don't (yet) have any other instrument than my refractometer to help me by giving me measurements for this, the insight into the problems and different possibilities has been interesting. Unfortunately I work in a physics laboratory, not a chemistry... I guess I could find someone at he university to help me, but I don't quite feel it would be worth the effort for a single vine. I will probably pick one day next week, once the weather becomes a bit better than the autumn storm we are experiencing today. And I will try to ferment the juice, even though I might not even get one full bottle of wine from it. I have earlier fermented a small amount of apple juice in a wine bottle without problems, so I think it should be worth a try.I'll let you know the result.Cheers and thanks,Anders

you might think of this as dividing grape varieties into two groups. with some varieties - say the cabernets - what is now called physiological ripeness is fairly important - avoids the methoxypyrizine for instance. with other varieties - riesling in particular, the grape has good flavors beginning well before 82 degrees and before the browning of seeds(and stems are often mentioned as well). the flavors of riesling change as they get riper but are pleasant all along the scale. it sort of depends on what style you want. with extremely ripe grapes you are almost committed(with riesling at least)to leaving some RS; while if you want a dry wine - less ripe would be appropriate.

so now the question is: which varieties fall into which groups?

thomas, could you provide a link to stevenson's article of riesling? please?

Today I decided to harvest my grapes, which was lucky indeed, because when I came out to the vine, the was a magpie jumping behind it and a few of the grapes had disappeared! The must I got after pressing the grapes in a potato press(!) had 81 Oe, 19 Bx. I now have the impressive amount of 220 ml of must that I will try to ferment. Wish me luck!